From 75a06189fc508a2acf470b0b12710362ffb2c4b1 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 16 Jul 2015 14:10:17 +0200
Subject: [PATCH] genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD
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The resend mechanism happily calls the interrupt handler of interrupts
which are marked IRQ_NESTED_THREAD from softirq context. This can
result in crashes because the interrupt handler is not the proper way
to invoke the device handlers. They must be invoked via
handle_nested_irq.
Prevent the resend even if the interrupt has no valid parent irq
set. Its better to have a lost interrupt than a crashing machine.
Reported-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
---
kernel/irq/resend.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
index 9065107f083e..7a5237a1bce5 100644
--- a/kernel/irq/resend.c
+++ b/kernel/irq/resend.c
@@ -75,13 +75,21 @@ void check_irq_resend(struct irq_desc *desc, unsigned int irq)
!desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
#ifdef CONFIG_HARDIRQS_SW_RESEND
/*
- * If the interrupt has a parent irq and runs
- * in the thread context of the parent irq,
- * retrigger the parent.
+ * If the interrupt is running in the thread
+ * context of the parent irq we need to be
+ * careful, because we cannot trigger it
+ * directly.
*/
- if (desc->parent_irq &&
- irq_settings_is_nested_thread(desc))
+ if (irq_settings_is_nested_thread(desc)) {
+ /*
+ * If the parent_irq is valid, we
+ * retrigger the parent, otherwise we
+ * do nothing.
+ */
+ if (!desc->parent_irq)
+ return;
irq = desc->parent_irq;
+ }
/* Set it pending and activate the softirq: */
set_bit(irq, irqs_resend);
tasklet_schedule(&resend_tasklet);